Q 01/05

Which physical effect lets a solar cell turn sunlight directly into an electric current, with no moving parts?

A) Piezoelectric effect

B) Hall effect

C) Thermoelectric effect

D) Photovoltaic effect

Answer · why

D) Photovoltaic effect

The photovoltaic effect frees electrons that stay inside the semiconductor and flow as current; in its close cousin, the photoelectric effect that won...

Q 02/05

Which country held the largest installed wind power capacity globally at the end of 2024?

A) China

B) Germany

C) United States

D) India

Answer · why

A) China

China ended 2024 with more than three times the wind capacity of the second-placed United States, yet as late as 2009 the US still led the world.

Q 03/05

Which folk singer did the US government hire in 1941 to write songs celebrating the Columbia River's new hydroelectric dams?

A) Pete Seeger

B) Burl Ives

C) Woody Guthrie

D) Lead Belly

Answer · why

C) Woody Guthrie

Woody Guthrie spent one month on the federal payroll and wrote 26 songs for a documentary about the dams, among them 'Roll On, Columbia'.

Q 04/05

Which geothermal plant technology uses a low-boiling secondary fluid to turn a turbine?

A) Dry steam

B) Flash steam

C) Hot dry rock

D) Binary cycle

Answer · why

D) Binary cycle

Binary cycle plants pass the geothermal water through a heat exchanger, so it never touches the turbine and goes straight back underground; that lets ...

Q 05/05

What process lets sealed tanks on farms turn manure and food waste into methane-rich biogas?

A) Flash pyrolysis

B) Windrow composting

C) Anaerobic digestion

D) Plasma gasification

Answer · why

C) Anaerobic digestion

Anaerobic digestion is microbes breaking down organic matter without oxygen; the biogas they give off is mostly methane and carbon dioxide and can be ...